The Pacific Symphony, like other orchestras around the world, is always on the prowl for new ways to bring younger listeners into the fold, and this week the Orange County-based organization is trying perhaps its most ambitious gambit to date with the four-day Wavelength Festival in Costa Mesa.

From Thursday through Sunday, the orchestra will host a broad spectrum of musicians from beyond its usual world of Mozart, Beethoven, Stravinsky and Copland, with concerts at the Pacific Amphitheatre, starting with the blues, rock, folk and pop of Bonnie Raitt and Keb' Mo'.

That will be followed Friday by an indie rock night with the Airborne Toxic Event, then an electronic dance music program Saturday curated by KCRW-FM music director Jason Bentley with British producer Bonobo and mash-up expert DJ Z-Trip. On Sunday, the festival concludes with a Pink Floyd tribute band performing the British rock group's 1973 classic "Dark Side of the Moon" album with backing by the orchestra, which also will join several of the other festival performers.

"I remember hearing Pink Floyd's 'Dark Side of the Moon' when it first came out and what it meant to me as a symphonic musician to hear the orchestra behind this great group we idolized," Pacific Symphony music director Carl St.Clair said.

"Or when 'Yesterday' came out with Paul McCartney singing with a string quartet, or when the Moody Blues came out with their album with a symphony orchestra. Here were these musicians like Emerson, Lake & Palmer, or Jethro Tull's Ian Anderson, who were definitely classically trained musicians stepping out of that into another world. I kind of think we're doing the same thing — in reverse."

The Airborne Toxic Event will get to sonically expand many of its songs in collaboration with the orchestra, while a small group of string players will work in tandem with Bonobo and Z-Trip.

"One of the challenges in working together with the orchestra is in the symphonic world, it's not like a jam band," Bentley said.

"You can't just fly stuff in and go with the flow, which is the way a lot of DJs work. There are some things that just won't work with an orchestra. But we're going to nail it down and find a way to give Z-Trip the freedom to be the really creative mash-up guy we know him to be."

Raitt will deliver a full set with her regular touring band. Even though she's not collaborating with the orchestra this time out, she has become a big fan of those kinds of performances.

"It's a really great overlap," Raitt said. "A lot of classical music composers are drawing from the same folk-music strains I emerged out of."

Noting her upbringing as the daughter of Broadway singer John Raitt, she added, "I'm a Broadway kid and I'm used to the idea of having trombones backing me doing a counter-line. It's a natural extension for people of our generation to get out of the box and listen to what this music can sound like with an orchestra, and programs like this allow people who are more highbrow to open it up a little bit. I think people's musical tastes are pretty broad these days."

"It's an experiment," orchestra President John Forsyte said. "We have a new board chairman, Mike Kerr, who's younger and is really encouraging the staff and Carl to take more risks, both within traditional orchestra settings and in nontraditional settings and venues."

Getting blues enthusiasts, progressive rock fans or the electronic dance music crowd to become season subscribers may be the best-case-scenario goal, but on a more pragmatic level Forsyte said the Wavelength Festival is more about expanding the experience both for audience and orchestra members.

The Pacific Symphony has been implementing that idea in various ways in recent years. Earlier this month, the orchestra's "Roll Over, Beethoven — From Rock to Bach" concert at Irvine's Verizon Wireless Amphitheater for its summer season, classical chestnuts alternated with performances of rock classics. The famous fate-knocking-on-the-door theme of the first movement of Beethoven's Fifth Symphony, for instance, was followed by a Chuck Berry imitator reeling off "Roll Over Beethoven."

Several months earlier, the Pacific programmed a night of music composed for video games, with a half-dozen of the scores' composers taking turns on the podium to lead the orchestra. "That's one of those things that could only happen in Southern California," Forsyte said.

"We're taking a page from some of the greater pop music festivals, where you have an eclectic blend of a lot of different artists concentrated in a short period," Forsyte said. "It's something we thought would be fun to experiment with."